1. Field of the Invention
The present invention generally relates to a method for determining the concentration of blood glucose, and more particularly to a method for determining a peak value of a rising curve to determine the concentration of blood glucose.
2. Description of the Prior Art
In the past, many systems have been developed for monitoring blood characteristics. For example, devices have been developed which are capable of determining such blood characteristics as blood oxygenation, and blood glucose concentration. However, significant difficulties exist when attempting to specifically determine blood glucose concentration accurately using noninvasive blood monitoring systems such as by means of spectroscopic measurement.
The difficulty in determining blood glucose concentration accurately may be attributed to several causes. Firstly, within the bloodstream, the blood glucose is typically found in very low concentrations (e.g., on the order of 100 to 1000 times lower than hemoglobin) so that such low concentrations are difficult to detect noninvasively, and require a very high signal-to-noise ratio. Additionally, with spectroscopic methods, the optical characteristics of glucose are very similar to those of water that is found in a very high concentration within the blood. Thus, where optical monitoring systems are used, the optical characteristics of water tend to obscure the characteristics of optical signals due to glucose within the bloodstream.
Furthermore, dry phase reagent test strips incorporating enzyme-based compositions are used extensively in clinical laboratories, physicians' offices, hospitals, and homes to measure the concentration of the compositions in the biological fluids. These strips have, for example, measured glucose, cholesterol, proteins, ketones, phenylalanine, or enzymes in blood, urine, or saliva. Measuring glucose concentration in samples of whole blood is a particularly common use. In fact, test strips have become an everyday necessity for many of the nation's several million people with diabetes.
Some test strips contain a testing reagent that turns a different shade of color depending on the concentration of glucose in a blood sample that has been applied to the strips. The blood glucose concentration is measured by inserting a strip into a meter that is basically a reflectance photometer, which determines the concentration from the change in color caused by the reaction between the testing reagent and blood glucose. The testing reagent typically contains an enzyme, such as glucose oxidase, which is capable of oxidizing glucose to glucose acid lactone and hydrogen peroxide; an oxidizable dye; and a substance having peroxidative activity, which is capable of selectively catalyzing oxidation of the oxidizable dye in the presence of hydrogen peroxide.